Surgery – Diagnostic testing – Detecting nuclear – electromagnetic – or ultrasonic radiation
Reexamination Certificate
2000-05-26
2001-12-11
Lateef, Marvin M. (Department: 3737)
Surgery
Diagnostic testing
Detecting nuclear, electromagnetic, or ultrasonic radiation
C600S451000, C600S561000
Reexamination Certificate
active
06328694
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the field of ultrasound apparatuses and methods for non-invasive medical diagnostics and treatment.
BACKGROUND OF THE INVENTION
In connection with performing medical diagnostics on the brain, it is often helpful to measure the variation, contraction or dilation, of blood vessels in the brain.
Currently known methods involve injection of radioactive or contrast-enhancing substances into the bloodstream in order to observe and learn about variations in blood flow in the brain between migraine attacks and normal conditions. Examination is also possible by the invasive method of introducing probes (electrodes) directly into the brain.
Currently known measurement methods for measuring blood flow to and in the brain include Isotope Diagnosis (ID) and Transcranial Doppler ultrasonography (TCD). Isotope Diagnosis is invasive and can only be performed by intermittent sampling measurements, rather that continuous measurement in real-time.
TCD is noninvasive and does give real-time measurement. However, the accuracy of the measurement is highly dependent upon the angle of the probe relative to the skull, and the skill of the operator. In addition, TCD does not measure the volumetric velocity of the blood flow and does not give precise measurement of the contraction or dilation of blood vessels in the brain. This imprecision is caused by the fact that TCD can only be used to observe a sector or large area in the brain, instead of a localized point. In addition, TCD uses ultrasound waves at a frequency of 2 MHz, which, for an estimated 15-40% of the population, do not actually reach the interior of the cranium, because of high attenuation of the ultrasound waves in the bone tissue of the cranium. In those cases, where there is a response from the skull or via “acoustic windows,” such as the temporal bones (orbital regions or foramen occipital magna), the acoustic reflections detected are only from the magistrial and proximal blood vessels. In addition to these reflected signals, this method also detects reflections from the brain and from other, non-cranial, blood vessels. The result is a noisy signal that does not allow precise determination of the depth of the measurement point. This does not allow measurement of individual blood vessels or their blood flow with any precision. Use of ultrasound technology as a diagnostic tool is discussed, inter alia, in the book entitled “Textbook of Diagnostic Ultrasonography,” 4.sup.th edition, by Mosby, pages 682-686.
It is also useful in connection with medical diagnostics of the brain to initially determine, and then monitor over time, the pressure in the brain. This pressure is commonly referred to in the art as intra-cranial pressure.
As a general rule, tissues in the body swell when traumatized. In order to heal, such tissues require oxygen. There are special circumstances with respect to brain tissue which makes the situation even more critical. The brain rests inside a bone casing, and there is little or no room for it to expand. When the brain swells, it experiences more trauma. Because it is encased within the skull, the swelling of the brain causes parts of the brain to be compressed. This compression decreases the blood flow and oxygen to parts of the brain which, in turn, causes more swelling. The more damage the brain receives, the more oxygen it needs, and the more it swells. Swelling is caused, e.g., by leakage from blood vessels. This leads to a rise in pressure within the brain. This rise in pressure rapidly equals the arterial pressure, thereby effecting the blood flow to the brain. The diffused pressure which decreases blood flow affects the ability of the cells within the brain to metabolize properly. The cells are unable to eliminate toxins, which toxins then accumulate in the brain. This phenomenon leads to a spiraling effect, which in effect is what kills brain-injured individuals who do not get prompt medical attention.
In response to a trauma, changes occur in the brain which require monitoring to prevent further damage. The size of the brain frequently increases after a severe head injury. This is referred to in the art as “brain swelling” and occurs when there is an increase in the amount of blood in the brain. Thereafter, water may collect in the brain (referred to in the art as “brain edema”). Both brain swelling and brain edema result in excessive pressure in the brain. The pressure in the brain is referred to in the art as intracranial pressure (“ICP”). It is essential that excessive ICP be identified and monitored so that it can be immediately treated. Treatment of brain swelling can be difficult, but it is very important because brain swelling in turn causes reduced amounts of both oxygen and glucose available to the brain tissue. Oxygen and glucose are both required by the brain to survive. The cranial cavity of the skull contains approximately 78% brain, 12% blood and vessels, and 10% cerebrospinal fluid (CSF). Intracranial volumes enclosed within the rigid container of the skull are fixed. An increase in the volume of one of these components requires an equivalent decrease in another of these components in order for the volume in pressure to remain constant. Increases in ICP occur as a result of this volume-pressure relationship. When there is an increase in any of these three components, the body tries to compensate by reabsorbing CSF and decrease intracellular volume.
In order to treat excessive ICP, physicians have a number of different methods available at their disposal, including the use of medications which help draw fluid out of the brain and into blood vessels; medications which decrease the metabolic requirements of the brain; medications which increase blood flow into the brain; and surgical procedures which are used to either reduce small amounts of fluid or remove the damaged brain tissue.
Surgical procedures further include removing any hematomas (blood clots) which are pressing on the brain, or surgically repairing damaged blood vessels to stop any further bleeding. In severe cases, portions of the brain that have been damaged beyond recovery may be removed in order to increase chances of recovery for the healthy portions of the brain. A shunt or ventricular drain may be used to drain off excess fluids. The overall goal of the neurosurgeon is to maintain blood flow and oxygen to all parts of the brain, thereby minimizing the damage and increasing the prospect of survival and recovery.
The normal values for intracranial pressure (ICP) at the level of foramen of Monro are approximately 90-210 mm of CSF in adults and 15-80 mm of CSF in infants. Increased ICP can occur as a result of an increased mass within the limited volume of the cranium. Examples include an increase in CSF volume, cerebral edema, and growing mass lesions such as tumors and hematomas. Cerebral edema is the increase in brain tissue water causing swelling. It may occur secondary to head injury, infarction or a response to adjacent hematoma or tumor. Uncorrected increased ICP can lead to further brain damage due to the pressure and inadequate blood perfusion of neurological tissues. The treatment for increased ICP includes removing the mass (tumor, hematoma) by surgery, draining CSF from the ventricles by a drain or a shunt, hyperventilation, steroids, osmotic dehydrating agents, and barbiturates.
Increased ICP will reduce cerebral blood flow, leading to ischemia. If blood flow is constricted for more than four minutes, an individual can experience irreversible brain damage. With constricted blood flow, cells become damaged, leading to more edema, causing more increased ICP.
The principle causes of elevated ICP include traumatic head injury (e.g., edema, intracranial hemorrhage, and hydrocephalus), infection, and tumors.
Treatment of elevated ICP can be accomplished by CSF drainage; decreasing the edema via the use of strong drugs such as diuretics; ventilation (mechanical and hyperventilation); cerebral perfusion pressure control (blood pressure control, fluid restriction); and p
Davidson Davidson & Kappel LLC
Imam Ali M.
Inta-Medics, LTD
Lateef Marvin M.
LandOfFree
Ultrasound apparatus and method for tissue resonance analysis does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Ultrasound apparatus and method for tissue resonance analysis, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Ultrasound apparatus and method for tissue resonance analysis will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2590827